77462-26-1Relevant articles and documents
A phosphide-bridged cluster synthesis with metal-coordinated diphosphine. 1. Synthesis and characterization of FeCo2(μ-CO)(CO)7(μ-PPh2)2
Young, David A.
, p. 2049 - 2054 (2008/10/08)
A new cluster FeCo2(μ-CO)(CO)7(μ-PPh2)2 was synthesized in 71% yield by the reaction of Fe(CO)4(PPh2PPh2) with Co2(CO)8. Structural characterization by single-crystal X-ray diffraction determined the following: space group P1 (No. 2) with Z = 4 and unit cell dimensions a = 14.694 (4) A?, b = 20.599 (5) A?, c = 10.715 (3) A?, α = 90.36 (2)°, β = 94.83 (2)°, γ = 87.62 (2)°, and V = 3228.7 A?3. Diffraction data (0° 1 = 0.068 and R2 = 0.079 for 3759 independent reflections. The unit cell contains two stereoisomeric pairs of molecules designated A and B. Each contains a triangular core of FeCo2 with a PPh2 ligand bridging each Fe-Co bond. One of the PPh2 bridging ligands is above and the other below the FeCo2 plane. Two terminal carbonyls are bound to the Fe, three to one Co, and two to the other Co. A semibridging carbonyl bridges the Co-Co bond and resides closer to the Co with the two terminal carbonyls. A low-temperature 13C NMR study (on a 13CO-enriched sample) and a 31P NMR study demonstrated a carbonyl-exchange process which we postulate contains four distinct steps. Cyclic voltammetry showed three one-electron reduction waves for the complex at -1.01, -1.45, and -1.75 V vs. a Ag (0.10 N AgNO3) reference electrode in acetonitrile solution. Whereas the first and third waves appear to be reversible at slow scan rates, the second appears reversible only at high scan rates. Reduction of the complex with sodium amalgam gave a new anionic derivative. Protonation of this derivative with H3PO4 returned the neutral starting complex in high yield.
